A Wearable, Multimodal Sensing System to Monitor Knee Joint Health

Abstract

Objective: We designed and validated a wearable, multimodal sensor brace for knee joint health assessment. Methods: An embedded-, two-microcontrollerbased approach is used to sample high-throughput, multi-microphone joint acoustics (46.875 kHz) as well as lower-rate electrical bioimpedance (EBI) (1/46.17 s), inertial (100-250 Hz), and skin temperature (1 Hz) data, and these data are saved onto microSD cards. Additionally, a flexible, 3D-printed brace houses the custom circuit boards and sensors to enable wearable sensing. Results: The system achieves 9 hours of continuous joint sound recording, while the EBI, inertial, and temperature sensors can sample for 35 hours using 500 mAh batteries. Further, for the entirety of these continuous recordings, there were no dropped samples for any of the sensors. Lastly, proof-of-concept measurements were used to show the system's efficacy for recording joint sounds and swelling data. Conclusion: This is, to the best of our knowledge, the first, completely untethered wearable system for multimodal knee health monitoring. Significance: The proposed smart brace may facilitate in-clinic or at-home measurements for joint health assessment.

Assessment of Hip and Knee Joints and Implants Using Acoustic Emission Monitoring: A Scoping Review

“…A stationary system for joint acoustic analysis was discussed in [40] and wearable devices for the evaluation of the knee's health were described in [35], [79]- [82]. While all the identified devices and sensors were intended for joint condition assessment, some specific applications were mentioned, such as AE source detection [74], tribological condition evaluation and prediction of femur rupture [81], osteoarthritis evaluation [75], [76], injury monitoring [35], [83], and quantifying rehabilitation stage [79].…”

“…Knee angles were frequently measured along with AE by means of electrogoniometers in stationary systems [40] or IMUs in wearable solutions. A temperature and a lower-rate electrical bioimpedance measurement were also included in [82] to provide complex knee assessment, including swelling, activity level, and joint angle.…”

Flexible PCB Failures From Dynamic Activity and Their Impacts on Bioimpedance Measurements: A Wearable Case Study

“…Circuits and systems designers are often focused on the sensing circuitry of bioimpedance measurements. Research efforts often target improving the circuitry for current injection, voltage sensing/amplification, and filtering [ 30 ], [ 31 ]. However, it is also important for designers to understand the interface of the circuits and systems to the biological tissue and how it can impact their measurements.…”

Smart sensor tights: Movement tracking of the lower limbs in football

“…These IMUs consist of a box, typically with a size of 30 mm × 40 mm × 10 mm, containing all electronics including the battery. In most cases, the modules are tied around the limbs, chest, or hands (Stiefmeier et al, 2008; Rawashdeh et al, 2016; Anwary et al, 2018; Chen et al, 2020; Teague et al, 2020). Other researchers attach them to the skin with an adhesive at predetermined locations (Gaidhani et al, 2017; Hu et al, 2020).…”